Sprocket chains of the type to which the present invention relates are well known; for example, the referenced U.S. Pat. No. 4,344,761, Steuer, describes a chain which is composed of packs of side bars which form successive links. The links are connected with one another for articulation. Thrust or pressure pieces act transversely of the longitudinal direction of the chain for friction force transmission between cone disk pulleys and the side bar chain. The length of selected ones of the links between associated articulations are made differently from those of the remainders of the links of the chain.
Various types of these sprocket chains are known. For example, the sprocket chains described in the referenced U.S. Pat. No. 3,089,346, Dittrich et al, can use rocker elements to form the links with the pressure element for friction or force transmission. These rocker elements cross a packet or cartridge of side bar links, as well as clamping brackets to hold the side bars together. The rocker elements extend transversely to the longitudinal direction of the chain and pass through suitably provided openings, so that the end faces of the rocker elements can engage in frictional contact with the cone disks of the transmission. U.S. Pat. No. 3,364,767, describes a construction in which the links of the chain are articulatedly connected by joint bolts. T-shaped pressure elements are fitted between the respective joint bolts and inserted into the packages or groups of links; the pressure elements provide for the required force transmission.
More recent constructions, as exemplified for example by U.S. Pat. No. 3,353,421, Ketterle et al, as well as by U.S. Pat. No. 3,916,709, Steuer et al, utilize the pairs of the rocker elements interconnecting the links simultaneously as the pressure elements to provide frictional engagement with the cone disks or cone pulleys of the transmission.
German Utility Model DE-GM 19 79 421 describes a different construction, in which packages or groups or links are provided forming the respective link elements of the chain, interconnected by link bolts. The packages of the links, which include the side bars, are surrounded by pressure rings, positioned between the locations of the joint bolts. The pressure rings are rotatable about an axis parallel to the longitudinal direction of the chain, for rotation about the packages of links. These pressure rings are in frictional engagement with the cone disks or cone pulleys of the transmission.
When an articulated chain runs into the pulley pair formed by facing cone pulleys, impacts arise as the chain enters the conical portion between the pulleys. These impacts, between the pressure elements and the cone pulleys themselves, generate undesired noise.
To solve the noise problem, it has been proposed (see U.S. Pat. No. 4,344,761, Steuer) to change the spacing between the individual links in order to interfere with resonance phenomena, and thus dampen or break up any resonant noise. This change in the division spacing between links has to be carefully constructed, so that the energy transmission between the chain and the pulleys is not interfered with; further, the construction of the chain should not basically change; it must be interchangeable with other chains. The length of selected ones of the links, between associated articulations, are made differently from those of the remainder of the links of the chain to minimize vibrations between the chain and the associated cone pulleys during operation of the transmission.
It has been found when the difference between length of link is in the order of 30% of "normal" length, difficulties arise in high-performance chains. Particularly, if this type of construction is used in a triple side bar arrangement, in which a plurality of links are stacked laterally, with respect to the operating direction of the chain, lateral guidance of the chain can be lost with respect to adjacent links. If adjacent lateral links slip sideways, end-engagement of the links may arise and, in operation, the chain could reach a position in which the links block each other, which, if sufficient power is applied to the chain, might result in rupture of the chain.